ON THE GEOLOGY OP ST. JOHN. 257 



1st They overlie the Dadoxylon sandstone conformably (or 

 nearly so). 



2nd They underlie carboniferous deposits unconformably. 



3rd They partake of the flexures of the Devonian series, which 

 preceeded the formatiou of the Lower Carboniferous con- 

 glomerate. 



Their unusual metamorphism is evidently caused by the abun- 

 dance of volcanic debris with which the beds are charged. I 

 have connected them with the cordaite shales, but it is quite pos- 

 sible that the upper part may be altered beds of the Mispeck 

 group. 



Dynamical Features. — The thinly laminated strata of the St. 

 John group are in many places drawn up into sharp folds, having 

 oblique axes directed to the west and southwest, and inclined to 

 the horizon at various angles. The markings on the layers show 

 that they have been inverted in some places where these plica- 

 tures cannot be traced. The real thickness of the group may 

 therefore be much less than we might, from a cursory examina- 

 tion, be inclined to suppose. 



The grander folds of the Upper Devonian and older beds have 

 already been described. That these were induced at the close of 

 that epoch is evident, because the materials of which the frag- 

 mental rocks at the base of the Lower Carboniferous strata on the 

 Kennebeckasis are composed, have been derived from beds brought 

 to the surface by the abrasion of one of these folds, and because at 

 one locality these rocks rest on the upturned edges of the higher 

 Upper Devonian strata. Physically therefore, the line of separa- 

 tion between the two ages is strongly marked in southern New 

 Brunswick. 



This fact stands out with greater distinctness when we consider 

 that 2000 feet or more in vertical thickness of what had already 

 become solid rock, were removed from the tops of the folds in 

 the older beds, before the materials of which the Kennebeckasis 

 conglomerate is formed, were exposed. And we cannot well 

 avoid the conclusion that currents or other agencies of vast force 

 or long continuance (perhaps both), held sway over this region 

 at the opening of the carboniferous age. The wide hiatus between 

 the two series also excites the suspicion that the conglomerate 

 alluded to is not at the base of the carboniferous series. The gap 

 which intervenes may be narrowed by the bituminous shales, &c, 

 Can. N&t. 11 Vol. YIII. 



